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Identifier |
000465980 |
Title |
Excitation of heliumlike C4+ and O6+ projectile ions in collisions with He targets |
Alternative Title |
Μελέτη ατομικών διεγέρσεων δέσμης ηλιοειδών ιόντων C4+ και O6+ σε κρούσεις με στόχους He |
Author
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Λαουτάρης, Άγγελος Δ.
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Thesis advisor
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Τζούρος, Θεόδωρος
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Reviewer
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Μπενής, Εμμανουήλ
Λαγογιάννης, Αναστάσιος
Ρακιτζής, Πέτρος
Κομίνης, Ιωάννης
Αντύπας, Διονύσης
Dubois, Alain
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Abstract |
Using the APAPES (Atomic Physics with Accelerators: Projectile Electron Spectroscopy) project zero-degree Auger projectile spectrograph setup and the C4+ and O6+ He-like ion beams supplied by the 5.5 MV “Demokritos” tandem Van de Graaff accelerator, K-Auger projectile electron spectra measurements were performed, for 0.5-1.5 MeV/u collisions with He gas targets. He-like beams in general contain a mixture of 1s21S, 1s2s 1S 1S and 1s2s 3S components, so all three initial channels are considered. In particular, this work focuses on the following two collision processes:
X q+ (1s2) + He →X(q+1) + (1s2p22D) + He+(All) (Transfer-Excitation) (1)
↳X q+ (1s2) + e-A(θ=0ο) (2)
and
X q+ (1s2, 1s2s 3,1S) + He →X q+ (2s2p 3.1P ) + He(All) (Projectile Excitation) (3)
↳ X(q-1)+(1s) + e-A(θ=0ο) (4)
where Xq+refers to carbon C4+ or oxygen O6+ projectiles. The second line of each process indicates the emission of the Auger electron and its detection at theta=0 degrees.
In this thesis, the cross section for the production of the 1s2p22D, 2s2p 3P and
2s2p 1P states were determined, in order to study the transfer-excitation (TE), single and double projectile excitation atomic processes. The measurements are also accompanied by close-coupling (CC) calculations in which three-active electrons have been included for the first time (3eAOCC) 1, in an attempt to cast further light on these complex multi-electron processes.
The calculated cross sections for the production of 1s2p22D from 1s21S through TE, both for carbon and oxygen are found to be in agreement with zero-degree Auger projectile spectroscopy measurements covering the maximum of the resonance peak and its high energy wing. At lower energies, the theoretical results show a second maximum which is interpreted recently [1] through a nonresonant one-step transfer excitation mechanism.
In the case of 2s2p 3P and 2s2p 1P the 3eAOCC calculated cross sections were converted to Auger electron normalized yields for a direct comparison between theory and experiment, as 2s2p 3P and 2s2p 1P states can be populated by all three
1s21S, 1s2s 1S 1S and 1s2s 3S components through different processes. Although both theory and experiment trends appear to have a similar energy dependence, the theoretical results in this case are in general smaller than the experimental, leaving room for discussion on the possible reasons that this happens.
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Language |
English |
Subject |
Accelerator-based atomic physics |
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Auger electron spectroscopy |
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Doubly-excited states |
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Electron excitation |
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Electron transfer-excitation |
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He-like ions |
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Highly-charged ions |
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Ion-atom collisions |
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Li-like ions |
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Long-lived (metastable) states |
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Mixed-state ion beams |
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Projectile-ion electron spectroscopy |
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State-selective cross sections |
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Zero-degree Auger projectile spectroscopy |
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Ατομική φυσική με επιταχυντές |
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Διπλά διεγερμένες καταστάσεις |
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Ενεργές διατομές ατομικών καταστάσεων |
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Ηλιοειδή ιόντα |
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Κρούσεις ατόμων ιόντων |
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Λιθιοειδή ιόντα |
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Μετασταθείς ατομικές καταστάσεις |
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Μικτές δέσμες ιόντων |
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Σύλληψη ηλεκτρονίων με ατομική διέγερση |
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Υψηλά φορτισμένα ιόντα |
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Φασματοσκοπία δέσμης ιόντων μηδέν μοιρών |
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Φασματοσκοπία ηλεκτρονίων Auger |
Issue date |
2024-07-08 |
Collection
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School/Department--School of Sciences and Engineering--Department of Physics--Doctoral theses
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Type of Work--Doctoral theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/2/7/0/metadata-dlib-1720508537-831516-5804.tkl
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Views |
165 |